The use of plastics is establishing itself increasingly, in particular also in a wide range of fields of daily life. One example of many for the use of plastics lies in the use of plastics for container-like objects, such as plastics bottles or plastics canisters, for example. Plastics bottles as well as plastics canisters are generally closable vessels, which have a comparatively large cavity for accommodating goods, such as in particular of liquids (wherein the liquids can also be comparatively viscous substances, such as honey, gels and materials of this type; it goes without saying that the goods, which are to be accommodated in the vessel, can preferably also be pourable solids, such as granulates or powder, in particular hygroscopic granulates or powder, for example). Generally, the differentiation between bottles on the one hand and canisters on the other hand is made on the basis of the volume thereof, but, in parts, additionally or alternatively also based on the shape thereof. In the case of volumes of more than approximately 5 to 10 l, one typically refers to canisters, whereas one rather tends to speak of bottles in the case of lower volumes. Moreover, hollow bodies, which are rather cuboid-shaped, are rather identified as canisters, whereas there is a tendency to identify rather cylindrical bodies as bottle. In practice, the separation between canister and bottle is oftentimes fluid.
While the use of plastics containers for chemicals (also household chemicals, such as detergents, cleaning agents and the like, for example) has already established itself for decades for the most part, the use of plastics containers has also established itself to an increased extent in recent years for the packaging of food, in particular also of liquids, such as beverages, for example, in particular carbonated beverages the like, wherein a pressure of up to approximately 10 bar can be created in the containers.
Regardless of the intended use, it is generally desired for plastics containers (but also other containers) of a certain size to be provided with a type of handle, so as to make it possible to more easily carry or to more easily handle, respectively, the vessel. Even though it is also quite possible to realize handles by using “blind holes” (the opening for the handle is thus not continuous, but still has a type of separating wall, which separates two opposite handle recesses), it is generally desired for the opening for the handle to be continuous (“open”). Generally, such a design is considered to be more advantageous from an esthetic point of view. Moreover, the practical value of the handle generally increases, because this makes it possible for right-handers as well as left-handers as well as persons with different hand sizes to grip more easily.
It is furthermore desired that no sharp-edged and/or protruding edges and seams are present, if possible, in particular in the area of the handle (in particular in areas, in which the palm or the fingers, respectively, of the user come to rest). Such edges and seams are at least uncomfortable in response to carrying, they might even represent a certain risk of injury.
In the case of such handles, it is furthermore desired for the handle to be completely embodied as cavity, if possible. A larger inner volume for accommodating liquids can be provided in this manner. It is in particular useful thereby, if the respective cavity area is open (thus “upwards” and “downwards”) on both connecting points of the handle to the bottle body, so that, if possible, no “dead volume” remains under all conditions of use and tilt angles, in which residual amounts of liquid could collect.
Meanwhile, a further demand is for the respective object to be capable of being recycled in a particularly good and simple manner, if possible, after being used. This demand can in particular be fulfilled in that the respective object is made of a single material, if possible. However, in the case of so-called “multilayer blanks”, which are made of a plurality of materials, a good recyclability can now also be realized as a result of a suitable selection of material combinations and interconnections of the different materials, which are used. Presumably, the demand for a good recyclability will become increasingly important in the coming years.
It goes without saying that it should be possible to produce as well as transport the respective vessels as quickly and cost-efficiently as possible. This is of particular importance for comparatively low-priced products, such as for beverages (in particular drinking water, mineral water, sodas and the like), for example, or for certain (household) chemicals (for example anti-freeze agents for motor vehicle windscreen cleaning systems).
While methods, which are quite practicable and cost-efficient, do exist now for some plastics materials for embodying handles, which fulfill at least a majority of the mentioned demands, it is still difficult in certain fields of applications, such as, for example, in the food sector. This is so, because the use of PET is particularly advantageous in certain fields of application (such as, for example, in the above-mentioned food sector), because this material combines different advantageous characteristics. For instance, PET is advantageous in the food sector, because it is tasteless, comparatively stable (thus also suitable for accommodating carbonated beverages, for example), as well as comparatively gas diffusion-tight (or the gas diffusion-tightness, which is already present in any event, can easily be increased further, respectively, by means of suitable methods; this is necessary, for example, so that the oxygen contained in the atmosphere cannot penetrate into the bottle and can change the taste of the food there or can cause the food stored therein to spoil, respectively, or also if hygroscopic materials, such as powder and the like, for example, are accommodated in the container, and if the penetration of water (vapor) is to be prevented). Furthermore, PET is also transparent, which is considered to be an advantageous characteristic, specifically in the food sector. Reference is to also be made (without any claim to completeness) to the packaging of (household) chemicals (for example of cleaning agents and the like), as well as of cosmetic products (for example of perfumes or bath additives), as further fields of application, in which the use of PET can be advantageous.
However, a large problem of the use of PET is that two PET parts cannot be connected to one another or can be connected in a barely sufficient stable manner, respectively, with reasonable effort, if certain optical demands are to be fulfilled. Even though it is possible, for example, for two PET areas to be placed on top of one another and to be connected to one another by means of ultrasonic welding; the weld seam created hereby with a width of typically 1 to 2 mm, is oftentimes not sufficiently mechanically stable and the eye can generally optically recognize it easily, in parts even as milky-white (and non-transparent) web. However, problems occur, if two PET areas are to be connected, wherein the “optical indistinguishability” or “transparency”, respectively, of the material, is to be maintained in the area of the connection. The reason for this are the intrinsic characteristics of PET, because PET displays a strong tendency to crystallization (in part also identified as self-crystallization). In particular, a high crystallization tendency (typically in the minute range, partly also shorter) already results shortly above the glass transition temperature.
Methods for forming apertures or continuous handles, respectively, known in the prior art, in the case of which partial areas of the plastics container are initially deformed inwards, seals are formed subsequently and the “superfluous” wall areas created thereby are removed by means of die-cutting, cannot be used or can barely be used, respectively. This is so, because, in particular in the food sector or in the cosmetic/medical sector, the containers must be sufficiently tight with a very high degree of probability (so as to effectively prevent health risks as a result of contamination). Moreover, the containers are often treated comparatively roughly in the household sector (for example household chemicals, food, cosmetics), because they are brought along in bags or backpacks, for example, and/or because they can also fall to the ground from time to time. The plastics container must be able to absorb such loads, without resulting in leakiness thereof.
To solve the problem, partly improved PET mixtures, in the case of which seams can be connected to one another in an improved manner, have also been proposed. A use of such improved PET materials, however, still has not been able to establish itself, because the respective plastics materials are too expensive.
A further problem, specifically in the food sector (in particular in bottling plants), is the delivery of the bottles, which are still unfilled, to the bottling plant. A delivery (which is possible per se) of the completely formed bottles to the bottling plant, where they are filled, turns out to be highly uneconomical. This is so, because large volumes must be transported here with small weight, which leads to a correspondingly uneconomical transport (the same also applies for the storage of the bottles, which have not been filled yet).
Accordingly, it has established itself that so-called PET blanks (partly also identified as PETlings or as PET preforms) are delivered to the bottling plants. They have a compact shape. The PET blanks are made in separate plants, (generally) by means of injection molding processes and are delivered to the bottling plants as blanks. Here, they are deformed into the bottles, which are ready to be filled, by means of blow molding processes or stretch blow molding processes, respectively. Generally, the volume increases thereby by at least 10-times to 20-times. It can easily be understood, what transport effort or storage effort, respectively, can be saved hereby. Also for reasons of volume, it is desired for the handles to only be shaped or molded, respectively, at the bottling plant.
Accordingly, it should thus also be possible to maintain this type of logistics (delivery of PET blanks to the bottling plant, where they are blow molded or stretch blow molded, respectively, on site), when using PET bottles with handles. Moreover, it is particularly desirable that cost-efficient standard PET blanks, which are available in large quantities, can still be used.
Generally, methods or devices, respectively, which have been proposed so far, have at least one, but mostly several disadvantages in terms of the above description.
Publications EP 1 853 416 B1, EP 2 292 401 B1 as well as EP 103 413 B1 describe different production methods for stretch blow molded plastics containers, by means of which a container with a molded handle can be produced. An arrangement of two movable dies, which are located opposite one another, is thereby used in the stretch blow mold. These movable dies are moved towards one another (wherein it is additionally proposed in EP 2 103 413 B1 that they are initially moved away from one another prior to the movement, so that a type of bilaterally protruding fish eye forms; the wall thickness of the finished plastics mold is to become homogenous through this, if possible), so that two wall areas of the plastics container are connected to one another by applying pressure at a corresponding temperature (the dies are preferably heated). It is described as being generally advantageous for this purpose, if the molded handle is not continuous; thus if the walls, which are connected to one another, remain in the finished bottle (formation of handle recesses instead of a “real” handle). It is explained in part only as an option that a part of this “double wall”, which is created, can be die-cut. This already shows that a sufficiently fluid-tightness cannot be realized in the area of the handle recess seams with the methods proposed therein, in particular if parts of the double wall are die-cut. A further disadvantage is the creation of mostly sharp edges, if the respective walls are stamped out. As a result of the sharp edges, which are created, it is at least uncomfortable to carry the resulting bottle (in particular if the filled bottle is relatively heavy; in the case of a 2 l bottle, a weight of more than 2 kg is to be expected). In part, this sharp edge, however, can also represent a risk of injury, which is obviously unwanted.
A different approach is chosen in publications US 2011/0064899 A1, WO 2005/042230 A1, US 2005/0163952 A1, US 2004/0108627 A1, WO 01/12515 A1, EP 0 805 012 A1 or WO 96/33063 A1. In the case of these methods, however, it is necessary to use a specific PET blank. The production of such a PET blank, however, is comparatively extensive. Moreover, the resulting increased volume of the blanks makes it more difficult to transport them. A further problem is that it is necessary to insert the PET blanks into the blow molding machine with a correct angular position. This also represents additional effort. Moreover, in the case of most of the methods or devices, respectively, described therein, it is not possible to realize a hollow handle, which has the corresponding disadvantages. The method described in WO 2005/042230 A1 or the device described therein, respectively, is by far the most advanced. It is possible with this method (using a specific blank) to produce a bottle with a hollow handle, which, according to a special embodiment, can also be connected to the bottle body in a fluid-tight manner at both connecting points. However, a disadvantage of the methods described therein is not only the requirement of a specific PET blank, but in particular also the highly complicated machine, which works for a correspondingly long period of time, which is expensive to buy and which is maintenance-intensive.
Finally, the European patent specification EP 1 763 427 B1 also describes a plastics container with molded handle part as well as a method for the production thereof. According to the method described therein, it is possible to be able to use a cylindrically formed standard PET blank for forming the bottle. A type of “stub handle” is thus formed. An obvious disadvantage of the bottle described therein or of the production method described therein, respectively, is that the handle is only connected to the bottle body on one side and is accordingly in fluidic connection with the bottle cavity only on one side as well. Many perceive the resulting bottle shape as being esthetically unsatisfactory. Moreover, the handle only has a limited stability. A further problem is that residual liquid quantities can remain in the bottle in response to the use of the bottle described therein, which is unwanted as well.
There is thus still a demand for a plastics connecting seam, which is improved as compared to plastics connecting seams known in the prior art, for a plastics mold, which is improved as compared to plastics molds known in the prior art, for a method for producing plastics connecting steams or plastics molds, respectively, which is improved as compared to methods for producing plastics connecting seams or plastics molds, respectively, known in the prior art, as well as for a tool device, which is improved as compared to tool devices known in the prior art, for producing plastics connecting seams, plastics molds or for carrying out methods, respectively, for producing plastics connecting seams or plastics molds, respectively.